Horizontal axis wind turbines (HAWTs) typically have 2-5 blades mounted to a horizontal shaft that is attached to a gear box and a power generator. Turbines used in wind farms for the commercial production of electric power usually a tubular steel tower and three blades pointed into the wind by a computer control system. The tubular steel towers range from 200 to 300 feet high. The blades rotate at a rate of 10 to 22 revolutions per minute (RPM). A gear box is commonly used to step up the speed of the generator to 1,500 to 18,000 RPM. Some HAWTs operate at a constant speed but more energy can be collected by variable-speed turbines which utilize a solid-state power converter to interface to the transmission system.
Conventional HAWTs have many drawbacks including difficulty operating in near groud, turbulent winds; difficulty transporting the towers and blades; difficulty installing the massive towers; interference with radar by tall towers; creating opposition in local residents because of the appearance and sound created; fatigue and structural failure caused by turbulence; ice build up on the generator and blades; bird and bat fatalities; and unsteady forces transmitted through the machinery of the turbines due to aeroelastic forces on the blades.
The present disclosure relates to shrouded fluid turbines which exhibit advanced mixing and address the problems with HAWTs outlined above.